Sickle cutting knives have been used to cut plants, including, but not limited to, hay, grasses, small grains and the like, for many years. The knives typically include an elongate metal sickle bar, with a plurality of knife sections attached along the lengths thereof. The sickle bar normally slides along a stationary bar that has guards with knives bolted to a structural beam. The sickle bar and stationary bar are oriented so as to extend sidewardly along a forward edge portion of a header of an agricultural combine. The sickle bar with the knife sections moves back and forth between the guards so that the leading edges of the knife sections cross over the guards or through slots in the guards. This produces a shearing action which severs plant stems and stalks or other material captured between the knives and the guards. The sickle bar is normally driven reciprocally longitudinally by an oscillating device, which can include, but is not limited to, an eccentric shaft on a rotating hub, a  wobble drive, or a similar well known commercially available device. The sickle bar, which may weight as much as 60 pounds or more, typically must accelerate and decelerate two times per cycle as a result of the reciprocal movement. A typical speed for the sickle bar is up to about 16 hertz or cycles per second. The back and forth motion at a high cycle per second generates high acceleration values and high deceleration values that in turn generate high forces on the structural components. These high back and forth forces can have at least two negative effects, vibration at the sickle drive system that may be transmitted to other components of the machine causing discomfort for the operator, and fatigue failure of the structural components themselves.
One approach to overcome the above-listed negative effects has been to use two sickle bars each equal to one-half the sideward extent of the header, which are driven by two oscillating devices that are timed such that the sickle bars are traveling in opposite directions. However, this substantially increases costs, and it is difficult to sustain the timing of the two sickle bars. Other attempts include adding a weight equal to the sickle bar and traveling in an opposite direction at the drive end, but this also adds undesirable costs and weight.
Thus, what is sought is a drive for sickle cutting knives on a header of an agricultural combine which overcomes the problems, negative effects, and disadvantages and costs referenced above.